Biologic medicines account for a growing share of pharmaceutical spending, making efficient biosimilar use critical to expand patient access and generate health system savings. Yet uptake varies widely across OECD countries despite policies to encourage adoption. Originator companies often foster brand loyalty, affecting price sensitivity among prescribers and patients, raising concerns about whether promotion regulation influences competition with biosimilars. Promotion rules also differ widely across OECD countries – from strict limits to permissive regimes – with variation in oversight, permitted activities, and responsible authorities. While many drivers of biosimilar uptake are well studied, the role of promotion regulations remains underexplored, partly because promotional spending is difficult to track even where “sunshine laws” require disclosure, and because companies increasingly rely on indirect tactics targeting patient organisations, providers, and researchers. This paper assesses the impact of promotion regulations through a two-part analysis: a review of national frameworks and consultations with 29 key national stakeholders in seven countries, and an analysis of biosimilar uptake in oncology, rheumatology, and diabetes, focusing on market share and spending to identify links between regulatory stringency and adoption patterns.
